Combustion exhaust gas generated by furnaces, ovens, and diesel engines, contains nitrogen oxides (NOX), which are detrimental to environment. These NOx need to be reduced to form non-harmful gases such as N2, O2, H2O, before releasing to the ambient atmosphere. The NOX reduction can be accomplished by using ammonia gas (NH3) generated by mixing urea with water in a reaction shown in following,NH2CONH2+H2O(steam)→2NH3+CO2.(2X/3)NH3+NOX→XH2O+(X/3+1/2)N2.The water-mixed urea is injected into the exhaust stream before a selective catalytic reduction (SCR) converter where ammonia reduces NO and NO2 to N2 and H2O before exhausting to the ambient atmosphere. NO and NO2 have very different reduction rates with ammonia in the SCR converter. Therefore there is a need to know the individual amount of NO and NO2, in the exhaust gas for NOX reduction control and on board diagnosis (OBD). Existing commercially available exhaust gas NOX sensors can detect a total amount of NOX, but do not distinguish NO from NO2. Additionally, these sensors do not distinguish NH3 from NOX either. There is thus a need to have a NO2 sensor that can sense NO2 and be resistant to the interference sensing effect from NO and NH3.